Process for preparing p-benzoquinone diketals

Abstract

P-Benzoquinone diketals of the formula ##STR1## wherein R is H, an alkyl group having from 1 to 4 carbon atoms or a halogen atom, preferably H, CH.sub.3, Cl or F, are prepared by anodic oxidation of benzene or alkoxybenzenes of the formula ##STR2## wherein R has the aforesaid meaning and R.sup.1 is an alkyl radical having of from 1 to 4 carbon atoms In CH.sub.3 OH containing A. less than about 5% by weight of H.sub.2 O as well as B. about 0.2 to 15% by weight, calculated on the electrolyte, of at least a conducting salt selected from the group of ammonium and alkali fluorides, perchlorates, nitrates, tetrafluoroborates, hexafluorosilicates, hexafluorophosphates, benzene sulfonates, p-toluene sulfonates, quartenary ammonium and phosphonium fluorides as well as methylsulfates and additionally C. optionally about 0.5 to 10% by weight, calculated on the electrolyte, of a base to be oxidized with difficulty, preferably 2,6-lutidine, At a known anode made of a conventinal material, at a temperature of from about -20.degree. to +60.degree. C. When using as starting material an alkoxybenzene wherein the group OR.sup.1 contains an alkyl radical having of from 2 to 4 carbon atoms, the resultant p-benzoquinone tetramethyl diketal contains a small quantity of the corresponding trimethyl alkyl diketal having an alkyl group of from 2 to 4 carbon atoms in the alkoxy group. The diketals obtained may be converted into the corresponding p-quinones by acidic hydrolysis and are, consequently, valuable intermediates for the preparation of the latter as well as for the transformation into the corresponding hydroquinones, which in their turn may be used in known manner in photography, as stabilizers for monomers, as starting material for dyestuff preparation etc.

Dependencies are inferred from the claim text.